Comparison of Laboratory Microcosms and Field Responses to Copper

As a biological model, a Standardized Aquatic Microcosm has demonstrated trophic interactions and community recovery after pesticide treatment. Daphnia magna were temporarily eliminated by treatment with 0.5 mg/L copper, leading to changes in algal and rotifer densities. Algae were severely affected by treatment with 2.0 mg/L copper, demonstrating altered dominance and productivity. Recovery of treated communities after inactivation or isolation of active toxicant was demonstrated by populations attaining densities equivalent to control communities. Comparison with published studies of natural communities treated with copper indicates that similar trophic interactions have often been demonstrated, although field studies suggested that responses are quite variable.